As substitutes for pearls, noble metals and jewels there are conventionally known such as those in which the surfaces of base metals are colored or plated with other materials or synthetic resins are colored. Particularly, these days, materials manufactured in the field of high technology, such as mirror silicon plates, are used for ornamental parts of tiepins.
In the case of metals or silicon problems do not take occur if the unvarnished materials themselves are used, but if colored materials are used the coloring agent is likely to released thereby presenting a problem for durability. Further, as new jewel imitation it was difficult to obtain it having excellent ornamental properties such as in color, profoundness in color, durability, and gloss and shine. As ornamental silicon articles there are known such ones that in processing silicon as ornamental articles the surface of silicon is provided with an oxidized layer (Patent Kokai No. 3-39102) or with a silicon compound layer permeable but inert to visible rays (Patent Kokai No. 60-13599).